Setting and stiffening fabrics



02 ea-wa-aaai- United States Patent SETTING AND STIFFENING FABRICS George Kevin Mecklenburgh, Abergavenny, Harry Wade Peters, Llantarnam, and Stanley Shaw, Gritlithstown, England, assignors to British Nylon Spinners Limited, Pontypool, England, a corporation of Great Britain No Drawing. Application February 12, 1952, SerialNo. 271,238

Claims priority, application Great Britain April 24, 1951 13 Claims. (Cl. 117-66) This invention relates to the setting and stiffening of fabric consisting mainly of a synthetic linear polymer, for instance, a polyamide or polyester.

The fabric may be woven or knitted (including warpknitted) and may consist, for example, of polyhexamethylene adipamide. After being woven or knitted, as the case may be, such fabric must be subjected to a process of what is known as setting by heat. This process of setting is necessary in order that the fabric may preserve its smoothness or freedom from wrinkles during subsequent operations such as scouring, dyeing and washing, and may be effected by moist heat, e. g. steam under pressure, or by dry heat. Setting also has the important effect of minimising any dimensional changes occurring as a result of the aforesaid operations. It will be understood that the dimensions of the fabricshould be brought under control prior to setting, that is to say, the fabric should be held extended in the position it is desired that it assume.

For many purposes a stiff polyamide fabric is needed, for example,- in the case of leno-woven or marquisette fabrics, for use in lingerie and foundations garments. Stiff warp-knitted polyamide fabrics may be advantageously employed in the manufacture of shoes, blouses, collars and cuffs. Stiff polyamide fabrics likewise find useful application in the form of lace and net for trimmings. Moreover it is important that the stiffness be fast to washing and other hot wet treatment.

The present invention relates to a process for the setting and/or stiffening of fabric consisting mainly of a synthetic linear polymer, wherein the fabric has applied to it an aqueous solution of. a salt of an amphoteric metal, having a colourless oxide, with a volatile inorganic acid, and is thereafter submitted to a heating treatment in a dry hot zone at a temperature lying, to 170 C. below the melting point of the polymer, whilst maintained in the desired shape.

The present process of setting and stiffening may be carried out continuously. This, invention also includes fabric which has been set and! or stiffened in accordance therewith;

The fabric to which the. present process is applied may consist wholly of polyhexamethylene adipamide yarn, or, for instance, the warp and weft may consist of different polymers. Other polymers which may be used are polyureas, polyurethanes, polyesters, e. g. polyglycol terephthalate, or, for example, the following polyamides, namely, polyhexamethylene' sebacamide and polypentamethylene sebacamide, polytetramethylene adipamide, polyoctamethylene adipamide, polydecamethylene adipamide. Furthermore the present fabric may contain yarns comprising fibres of material other than synthetic linear polymers provided thereis little or no cellulosic or other material which is degraded by hot acid and provided also that the fabric consists mainly of a synthetic linear polymer, that is to say, contains at least 50% by weight thereof. Moreover the fabric may be in either a set or unset condition. Thus, if the original fabric possesses a degree of set less than that corresponding to the temperature and other conditions selected Within the process of this invention, then additional dimensional stability will be conferred upon 'it in addition to the stiffness imparted.

The expression volatile inorganic acid is to be understood to mean an inorganic acid which boils below C. By way of suitable salts of amphoteric metals with inorganic acids for use in the present invention there may be mentioned stannic chloride, zinc nitrate, zinc chloride and aluminium chloride.

The metal salt solution may be applied to the fabric in any convenient way, as by the immersion, spraying, padding or printing thereof; it may also be applied locally to the fabric, as for example, by printing. By the latter means, the stiffening effect of the present invention may be obtained only on selected portions of the fabric, and the pattern thus produced. It is advantageous that the fabric be maintained in a flat condition, that is to say, free from wrinkles or folds, when the solution is being applied.

The solution of metal salt employed may vary widely in its strength. Concentrations, for example, of zinc chloride, of /z%, 1%, 5%, 10%,15% can be used. The strength of the solution chosen is governed by the nature of the fabric on the one hand, and the effect desired, that is to say, the degree of set and stiffness, on the other. Generally speaking, the greater the amount of metal salt applied to the fabric and the higher the temperature, the greater the degree of set and stiffness obtained. The result will thus also depend on the weight of solution the fabric is allowed to retain; this can conveniently amount to 25 %-40% calculated on the weight of the fabric, for example. In most cases, however, whilst the degree of stiffness depends largely on the quantity of metal salt and the temperature, the degree of dimensional stability is mainly controlled bythe heating conditions, i. e. the temperature and duration of heating. The latter property is conveniently determined by the test quoted in Example 1. The degree of stiffness may conveniently be ascertained by determining the bending length, flexural rigidity'and bending modulus by the Shirley combined stiffness and creasing tester, as described in the Shirley Institute Test Leaflet No. DFl (1st edition, July 1946).

If desired, there may be included in the amphoteric metal solutions, swelling agents for the synthetic linear polymer of the fabric, e. g. benzyl alcohol, phenol, metacresol.

Owing to the tendency of the metal salts to hydrolyse, it is sometimes convenient to acidity them, for example, with hydrochloric or acetic acid, to prevent precipitation. In any case any residual acid on the fabric according to the invention is advantageously neutralised by washing with mild alkali, e. g. sodium carbonate, the neutrality being advisably controlled by spotting the fabric with an indicator.

be found to facilitate the feeding of the fabric into the apparatus containing thedry hot zone where the fabric is heated. The dry hot zone may consist of a hot ambient fluid, e. g. hot .air or. super-heated steam, or a hot dry surface, eg. a heated roller; radiant heat may likewise beused, e. g. infrared radiation. The heating, apparatus may conveniently comprise a suitably modified 2,734,001 Patented Feb. 7, 1956.

If any acid treatment is. desired, subsequent to the setting and stiffening process, thiscan be applied' stenter machine; the process may thus be easily operated as a continuous one. The fabric is submitted to the heat for a brief period which will depend on the temperature employed and on the structure of, and quantity of metal salt solution held by, the fabric, but may be, for instance, to 30 seconds.

As indicated, the present process of treating fabric in cludes maintaining the fabric during the heating treatment in the dry hot zone in the desired shape. A flat stiff fabric, for example, may be conveniently obtained by holding it on a pin tenter during the heating in the hot zone. The fabric may also, if wished, be set and stiffened whilst pleated, for instance. Moreover the stiffened fabric, prior to neutralisation with alkali, can be reheated and moulded to various shapes, e. g. for apparel.

By the present process fabrics are obtained of an excellent degree of stiffness and a pleasing handle, and consequently eminently suited for, amongst others, the purposes already referred to above. The fabric produced has the advantage of possessing good stability to hot air curing and hot wet treatments, both in regard to its dimensional stability and its stiffness. Nor does the present process impair the dyeing properties of the fabric treated thereby. Moreover the fabric tends also to acquire some dullness particularly when the degree of stiffness is fairly high, and this delustering effect is frequently regarded as highly desirable. Further advantages of the present invention lie in the added resistance to abrasion, often conferred on the fabrics, and the markedly reduced tendency to thread-slippage imparted to woven fabrics.

In the following examples, which are intended to illustrate but not limit the invention, the parts and percentages are by weight.

EXAMPLE .1

Five equal squares of polyhexamethylene adipamide locknit fabric, which have not been set, are impregnated with 10% aqueous zinc chloride, placed on an adjustable pin frame, dried under the conditions tabulated below, washed with cold water, neutralised with dilute aqueous sodium carbonate, and washed till neutral. The squares are then submitted to the following stability test. The results are given in the table below.

Stability test Condition the sample by maintaining it at 21.1 C. in an atmosphere of 65% relative humidity for 4 hours. Make suitable indelible markings to enable three cm. lengthwise and three 25 cm. widthwise dimensions to be measured. Immerse the sample without tension in boiling water and hold it therein for minutes (the water being at least 50 times the weight of the sample). Remove the sample, roll it without tension in a towel and squeeze it gently. Then allow the sample to dry at room temperature in a horizontal position. Recondition the sample as before and remeasure the two sets of three dimensions. Taking the average of each set calculate the change as a percentage of the original.

Oven temperature 116 0. 140 0. 160 C.

Time of heating 10 min. 5 min. 2% min.

Area shrinkage after stability te percent 7.1 3.0 0.8

EXAMPLE 2 A square of polyhexamethylene adipamide marquisette fabric, which has been set by dry heat at 216 C. for 30 seconds, is immersed in a 5% aqueous solution of zinc chloride and passed through nip rollers so that 25% (calculated on the fabric) remains. The so impregnated fabric is dried by heating in an oven at 130 C., rinsed with cold water, saturated with /2 aqueous sodium carbonate, and washed till neutral. The resulting fabric is stiff and has good dimensional stability.

EXAMPLE 3 A square of heavy warp-knitted shoe fabric, which has not been set, is saturated with 10% aqueous zinc chloride solution and centrifuged till the fabric holds 25% of its own weight of solution. The fabric is dried and further treated as described in Example 2; it is then eminently suitable for use in the manufacture of shoes.

EXAMPLE 4 EXAMPLE 5 A 50 cm. square of polyhexamethylene adipamide locknit fabric is held immersed during 30 seconds in an aqueous solution containing 10% zinc chloride (acidified with a few drops of hydrochloric acid) and 4% benzyl alcohol. The fabric is removed from the solution and the excess thereof expressed so as to leave 25 calculated on the weight of the fabric. The fabric is then set by exposure to air at 216 C. during 30 seconds whilst held with pins on a frame so that its dimensions are controlled.

The fabric is found to have very good dimensional stability and is rather stiff and thus suitable for shirt collars cuffs, jabots and sundry trimmings.

EXAMPLE 6 The fabric is treated as described in Example 5 except that the solution for pro-treatment consists of 5% aqueous zinc chloride. Similar results are obtained.

EXAMPLE 7 The fabric is treated as described in Example 5, the solution used for pre-treatment being replaced by an aqueous solution containing 10% zinc chloride (acidified with a few drops of hydrochloric acid).

EXAMPLE 8 Plain weave polyhexamethylene adipamide fabric of a light weight which has not been set but is free from wrinkles,'is saturated with a 5% aqueous solution of zinc nitrate and pressed so that the fabric retains 50% of its weight of solution. The fabric is then heated in an oven at 216 C. for 30 seconds on a pin frame. On removal from the oven the fabric is washed with water followed by an 0.2% aqueous solution of sodium carbonate and finally well rinsed with cold water, and dried.

The resultant fabric has excellent dimensional stability combined with an attractive silky gloss. The finish thus obtained is stable to 30 minutes treatment at 40 C. with soap solution containing 5 gm./l.

EXAMPLE 9 An unset heavy canvas fabric of polyhexamethylene adipamide is impregnated with a 15% aqueous solution of stannic chloride and passed through nip rolls allowing 50% retention of the solution. The fabric is then heated in an oven at 216 C. for seconds on a pin frame. After washing, neutralising and drying as described in the previous example, a stiff fabric of excellent dimensional stability is obtained which withstands the severe washing test, namely heating at 97-100 C. for 30 minutes in an aqueous solution containing 5 gm./l soap and 2 /2 gm./l sodium carbonate.

EXAMPLE l0 Example9 is repeated with the use of a 20% aqueous solution of aluminum chloride in place of the 15% solution of stannic chloride, the time of heating at 216 C. being 1 minute. A Well set canvas fabric is obtained at attractive stiffness.

Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is:

l. A process for Setting and stiifening fabric comprising at least 50% by weight of synthetic, high molecular weight linear polymer fibers, said process comprising the steps of treating said fabric with an aqueous solution of a salt, the cationic part of which consists of metal having an oxide which is both colorless, and amphoteric and the anionic part of which is derived from a volatile inorganic acid boiling below 100 C., so that said fabric carries sufficient of said aqueous solution to leave from to by weight of said salt on the fabric after drying and thereafter submitting said fabric to a heating treatment in a dry hot zone at a temperature lying 10 C. to 170 C. below the melting point of said polymer while maintaining the desired shape of the fabric, said heating at said temperature being suflicient to substantially increase the stiffness of the fabric.

2. Process as claimed in claim 1 wherein the salt is zinc chloride.

3. Process as claimed in claim 1 wherein the salt is zinc nitrate.

4. Process as claimed in claim 1 wherein the salt is stannic chloride.

5. Process as claimed in claim 1 wherein the salt is aluminum chloride.

6. A set and stiffened fabric obtained by the process of claim 1.

7. The process of claim 1, wherein the fabric carries suflicient of said aqueous solution to leave from 1% to 10% by weight of said salt on the fabric after drying.

8. The process of claim 1, wherein said high molecular weight linear polymer is selected from the group consisting of synthetic linear polyamides and synthetic linear polyesters.

9. The process of claim 1, wherein the linear polymer is polyglycol terephthalate.

10. The process of claim 9, wherein the salt is selected from the group consisting of stannic chloride, zinc nitrate, zinc chloride and aluminum chloride.

11. Process as claimed in claim 1, wherein the fabric consists wholly of the fiber-forming, high molecular weight synthetic linear polyer.

12. Process as claimed in claim 11, wherein the polymer is a synthetic linear polyamide.

13. Process as claimed in claim 12 wherein the synthetic linear polyamide is polyhexamethylene adipamide.

References Cited in the file of this patent UNITED STATES PATENTS 2,157,119 Miles May 9, 1939 2,251,508 Watson Aug. 5, 1941 2,425,334 McCreath Aug. 12, 1947 2,610,927 Foulds Sept. 16, 1952 

1. A PROCESS FOR SETTING AND STIFFENING FABRIC COMPRISING AT LEAST 50% BY WEIGHT OF SYNETHETIC, HIGH MOLECULAR WEIGHT LINEAR POLYMER FIBERS, SAID PROCESS COMPRISING THE STEPS FO TREATING SAID FABRIC WITH AN AQUEOUS SOLUTION OF A SALT, THE CATIONIC PART OF WHICH CONSISTS OF METAL HAVING AN OXIDE WHICH IS BOTH COLORLESS, AND AMPHOTERIC AND THE ANIONIC PARTS OF WHICH IS DERIVED FROM A VOLATILE INORGANIC ACID BOILING BELOW 100* C., SO THAT SAID FABRIC CARRIES SUFFICIENT OF SAID AQUEOUS SOLUTION TO LEAVE FROM 1/8% TO 10% BY WEIGHT OF SAID SALT ON THE FABRIC AFTER DRYING AND THEREAFTER SUBMITTING SAID FABRIC TO A HEATING TREATMENT IN A DRY HOT ZONE AT A TEMPERATURE LYING 10* C. TO 170* C. BELOW THE MELTING POINT OF SAID POLYMER WHILE MAINTAINING THE DESIRED SHAPE OF THE FABRIC, SAID HEATING AT SAID TEMPERATURE BEING SUFFICIENT TO SUBSTANTIALLY INCREASE THE STIFFNESS OF THE FABRIC. 